This invention relates to an image reading apparatus and an image forming apparatus including a first guide member and a second guide member opposed to each other to form a document feed path.
Some image reading apparatuses include a first guide member and a second guide member opposed to each other to form a document feed path, the first guide member being made of a transparent material, the second guide member including a shading correction white reference member, and an image read section for illuminating light through the first guide member to the second guide member and generating image data from reflected light. The image read section includes a mirror and a lens.
In such an image reading apparatus, a stain such as document ink attached to the first guide member or the second guide member will cause an image from image data to include a black image such as a black point or a black streak. The black image will reduce the image quality.
A well-known image reading apparatus is intended to analyze the image data according to a predetermined algorithm to identify a stained component (see, for example, Japanese Patent Laid-Open Publication No. 2001-186312). Depending on whether the image reading apparatus adopts the static document reading scheme or the fed document reading scheme and on whether the stain has a continuous pattern or an intermittent pattern, the image reading apparatus identifies the stained component such as the mirror, the paper feed roller, or the document glass.
The conventional image reading apparatus described in Japanese Patent Laid-Open Publication No. 2001-186312 attempts to identify the stained component according to the relationship between the document movement and the stain continuity. Although the image reading apparatus may thus identify the stained location in the document feed direction, it cannot identify the stained location in the direction perpendicular to the document image surface.
Thus, the conventional image reading apparatus described in Japanese Patent Laid-Open Publication No. 2001-186312 cannot determine whether the first guide member or the second guide member is stained. If the first guide member is stained, the image read from the document will show a black image. The black image will reduce the image quality of the image data of the document image. It is thus necessary to clean the first guide member. In contrast, if the second guide member is stained, no need to clean the second guide member to prevent the image quality reduction in which the image from the image data of the document image shows a black image.
Therefore, it is necessary to determine whether the first guide member or the second guide member is stained to determine whether the cleaning is needed to prevent the image quality reduction in the image data of the document image. Otherwise, it is likely to experience useless operations including the maintainer's unnecessary cleaning of the image reading apparatus and useless adjustment or replacement of the shading correction image data.
It is an object of the present invention to provide an image reading apparatus and an image forming apparatus capable of preventing a useless operation.